Magnetic recorder method and means



Oct. 11, 1949. A, LL 2,484,568

MAGNETIC RECORDER METHOD AND MEANS Filed Oct. 18, 1946 Era 77E!" Hu 6H 4. H0 WELL Patented Oct. 11, 1949 UNITED sTAr s PATENT OFFICE MAGNETIC RECORDER Mii'rnon AND MEANS Hugh A. Howell, Valparaiso, -Ind., assignor to The Indiana Steel Products Company, Chicago, Ill., a corporation of Indiana AppIicationOctober 18, 1946, Serial No. 704,035

H p 3 Claims, 1

This invention relates to a magnetic'recorder method and means, and more particularly, to a novel arrangement and method for giving base boost without necessitating any additional base energy input.

One of the particular problems which arises in any magnetic recording lies in the fact that base notes are not normally recorded with as high a relative energy level as are frequencies in the middle and high audio frequency ranges. Various arrangements have been provided for overcoming this shortcoming and have largely involved compensation for the low energy level of the low frequency notes by introducing additional base energy or by decreasing the response of the middle and high frequency ranges through some sort of an equalizer circuit.

One of the principal features and objects of the present invention is to providea novel method and means for providing base boost,without having any more base energy input and without providing an equalizer circuit which will dampen any of the other frequency ranges.

A further object of the present inventionis to provide a novel method and means for recording on a record member which includes a nonmagnetic base or carrier portion and a magnetizable portion.

Another and further object of the present invention is to provide a novel method and means for recording on a magnetic tape which is formed of a non-magnetic carrier coated with a magnetizable material.

A still further object of the present invention is to provide a novel recording and reproducin arrangement employing a pair of electromagnetic transducer heads disposed on opposite sides of a magnetic record member, the flux field set up in the non-magnetic gap of each of the heads being substantially parallel to the direction of travel of the record member.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization, manner of construction and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawing, in which:

Figure 1 is a diagrammatic view of a magnetic record member passing between a pair of electromagnetic transducer heads; and

Figure 2 is an enlarged fragmentary view of the pole tip portions of the two heads shown in Figure 1 with the record member passing thereby and in which the flux lines of the two heads are shown respectively in full lines and dotted lines.

As shown in Figure 1, a magnetic recorder embodying the teachings and principles of the present invention includes a magnetic record member It, such, for example, as a tape, having a non-magnetic base portion H and a magnetizable portion 12. By way of example and not by way of limitation, the base portion ll may be in the form of a paper tape, while the layer of magnetizable material l2 may be in the form of powdered magnetizable material cemented or otherwise suitably secured as a coating to the tape base portion II. The relative thicknesses of the base portion II and the coating of magnetic material 12 may vary through wide limits without'departing from the spirit and scope of the present invention, and the coating [2 has been illustrated as being abnormally thick merely for the purposes of illustration to show that it is distinct from the base portion II.

The magnetic record member In is arranged to pass between a pair of electromagnetic transducer heads l3 and I l. The head [3 includes a O-shaped core portion l5 forming confronting pole pieces having a non-magnetic gap 16 lying immediately above the record member It. The head I3 is also provided with a signal coil l1 which is arranged to be energized with a fluctuating electric signal whose characteristics are to be recorded on the record member l0.

Similarly, the electromagetic transducer head I4 includes a C-shaped core l8 having a non-magnetic gap 19 lying immediately under the record member ill. The head It is also provided with a signal coil 20 which is serially connected through the conductor 2! to the signal coil ll of the head 13. The other ends of the coils I1 and 20 are connected. through conductors 22 and 23 to any suitable energizing circuit or reproducing circuit.

As may be seen from an inspection of Figure 2 of the drawing, the positioning of the head IS on top of the record member I0 and the head 14 on the undersurface of the record member NJ has the effect of placing the magnetizable layer of material I2 of the record member ID immediately adjacent the ends or pole tips 24 and 25 of the head l3, but has the effect of spacing the pole tips 26 and 21 of the head 14 away from the layer of magnetizable material [2.

It has been found that when a magnetic record member in the form of a non-magnetizable base with a coating of magnetizable material thereon is caused to pass in contact with the poles of a magnetic head such as the magnetic head I3, all of the frequencies throughout the audio range are recorded on the record member, although the low frequency notes are not recorded at as high an energy level on the medium as are high frequency notes.

It has further been found that when a record member is passed over a head and the magnetizable coating maintained at a distance spaced 'from the pole tips such, for example, as spaced by a distance equal to the thickness of the paper tape forming the carrier for the magnetizable layer l2, only frequencies of under about 1,000 cycles are recorded. There is substantially no. recording of the high frequency notes or middle frequency notes.

It has thus been found that by connectinga. pair of electromagnetic transducer heads in series, such as the heads 13 and I4, and positioning one in contact with the magnetic layer I2 of magnetizable material and separating the head; therefrom by the thickness of the non.-magnetiz-- able carrier upon which the coating is carried, that a sufficient amount of base boost is obtained to counteract the reduced recording thereof by the head 83 when taken alone.

With an arrangement such as that shownthe drawing, it has been found that an extremely fiat frequency response may be obtained throughout a wide frequency range including the; lowfrequency range without resorting to an equalizer circuit or any separate circuit for introducing'additional base energy into the electric circuit.

The arrangement may also be used for reproducing by connecting the conductors 22 and 23- to, an output circuit rather than to an input circuit.

While I have shown a certain particular embodiment of my invention, it will, of course,gbe understood that I do not wish to be limited thereto, and I, therefore, contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of invention.

I claim as my invention:

1. An electromagnetic transducing instrument comprising a magnetic record member having a, non-magnetic baseportion and a coating ofmagnetic material, and a pair of electromagnetic transducer heads electrically connected for joint operation, one of said heads being positioned in close proximity to the magnetic coating of said record member and the other of said heads being positioned in close proximity to the base portion of said record member, thereby to provide inherent base. boost in said instrument.

2, An electromagnetictransducing instrument comprising an elongated magnetic record memher having a base portion of non-magnetic maerial and a coatingof magnetic material on one side only of said base portion, and a pair of electromagnetic transducer heads, each havin confronting pole pieces spaced along the length of said medium, electrically connected for joint operation and disposed on opposite sides of said record member, one in contact with said magnetic materialcnly and the other in contact with said base portion only.

3. An electromagnetic transducing instrument comprisingan elongated magnetic. record member having a base portion of non-magnetic ma,- erial and a coating of, magnetic: material on one side only of said base portion, and a pair of electromagnetic transducer heads, each havin confronting ,pole pieces spaced along the length of saidmedium, electrically connected for joint operation and disposed on opposite sides of said record member and in. substantial contact therewith, said heads being located directly opposite each otheriin their respective positions on opposite sides of said record member with one in contact with said magnetic material. only and the other in.

closeproximity totheopposite side of said record member.

-A.. HOWELL.

REFERENCES CITED,

The-following references are of record in the file of this (patent:

UNITED STATES PATENTS Behre June 2, 1942 

